In a production process of a liquid crystal display, the production procedures are generally carried out in an established order under the control of a computer production control system. The order of production procedures for a display substrate of a thin-film transistor liquid crystal display in a Twisted Nematic (TN) mode is different from the order of production procedures for the display substrate of the thin-film transistor liquid crystal display in an Advanced Super Dimension Switch (ADS) mode. With a color filter substrate of the liquid crystal display in the ADS mode as an example, the production procedures of the color filter substrate includes: a procedure for forming a transparent conductive layer, a procedure for forming a black matrix, a procedure for forming a color filter layer, a procedure for forming a spacer, etc. In the production process of the display substrate, the computer production control system controls the substrate to sequentially undergo respective predetermined procedures.
However, if failures of the computer production control system or other reasons (such as operator's misoperation) cause loss or disorder of the information stored in the computer production control system, it is impossible to determine the status of the substrate.